Determinants of fat oxidation during exercise in healthy men and women: a cross-sectional study.

The aim of the present study was to establish fat oxidation rates over a range of exercise intensities in a large group of healthy men and women. It was hypothesised that exercise intensity is of primary importance to the regulation of fat oxidation and that gender, body composition, physical activity level, and training status are secondary and can explain part of the observed interindividual variation. For this purpose, 300 healthy men and women (157 men and 143 women) performed an incremental exercise test to exhaustion on a treadmill [adapted from a previous protocol (Achten J, Venables MC, and Jeukendrup AE. Metabolism 52: 747-752, 2003)]. Substrate oxidation was determined using indirect calorimetry. For each individual, maximal fat oxidation (MFO) and the intensity at which MFO occurred (Fat(max)) were determined. On average, MFO was 7.8 +/- 0.13 mg.kg fat-free mass (FFM)(-1).min(-1) and occurred at 48.3 +/- 0.9% maximal oxygen uptake (Vo(2 max)), equivalent to 61.5 +/- 0.6% maximal heart rate. MFO (7.4 +/- 0.2 vs. 8.3 +/- 0.2 mg.kg.FFM(-1).min(-1); P < 0.01) and Fat(max) (45 +/- 1 vs. 52 +/- 1% Vo(2 max); P < 0.01) were significantly lower in men compared with women. When corrected for FFM, MFO was predicted by physical activity (self-reported physical activity level), Vo(2 max), and gender (R(2) = 0.12) but not with fat mass. Men compared with women had lower rates of fat oxidation and an earlier shift to using carbohydrate as the dominant fuel. Physical activity, Vo(2 max), and gender explained only 12% of the interindividual variation in MFO during exercise, whereas body fatness was not a predictor. The interindividual variation in fat oxidation remains largely unexplained.     

Skeletal muscle contractile and noncontractile components in young and older women and men.

To examine the influences of age, gender, and habitual physical activity level on human skeletal muscle composition, we developed a relatively simple magnetic resonance imaging method for the quantitation of leg anterior compartment contractile and noncontractile content. We studied 23 young (11 women and 12 men, 26-44 yr old) and 21 older (10 women and 11 men, 65-83 yr old) healthy adults. Analysis was by two-factor (age, gender) ANOVA. Physical activity, quantitated by three-dimensional accelerometer worn about the waist for 1 wk, was not different between groups. Men had larger contractile and noncontractile cross-sectional areas (cm(2)) than women, with no gender effect on percent noncontractile area. Young subjects had larger contractile areas and smaller absolute (cm(2)) and relative (percent total) noncontractile areas than older subjects. There was a significant linear relationship between physical activity and percent noncontractile area in older (r = -0.68, P = 0.002) but not young subjects. These data demonstrate a more than twofold increase in the noncontractile content of locomotor muscles in older adults and provide novel support for physical activity as a modulator of this age-related change in muscle composition.     

Obesity, leanness, and mortality: effect modification by physical activity in men and women

The 13-year mortality from BMI, body fat (BF), and fat-free mass (FFM) was examined among active and sedentary adults. In total, 2,819 men and women aged 35-65 years in 1987/1988, participating in the Danish MONICA project, were included, and followed for 13.6 years for total mortality. In men, physical activity modified the health hazard of both a high and a low BMI, and the U-shaped association disappeared among the active (hazard ratio (HR) = 0.86, CI: 0.72-1.02). Among active men, FFM was inversely related to mortality (HR = 0.55, 95% CI: 0.40-0.77) whereas a direct positive trend was seen for BF. Among women, physical activity modified association between BMI and mortality, but the U-shaped association remained among the active. Among women, no significant associations were found between either BF or FFM and total mortality. All effects were independent of waist- and hip-circumferences. In conclusion, among men, physical activity may play an important role for the prevention of early mortality beyond its direct effects, by modifying the health hazard of both a high and a low BMI, and by lowering the risk associated with a high BF or a low FFM. Among women physical activity lowers mortality, but an effect-modifying potential of physical activity on associations between BMI or body composition could not be identified.     

Daily energy expenditure across the course of lactation among urban Bangladeshi women

Measures of energy intake of lactating women in developing countries show that intakes are often lower than those recommended by international bodies, while fat-mass losses are often substantially less than the 3-4 kg used in the calculations of recommendations, suggesting that physiological adaptation must be commonplace among such women. The cost of lactation may be met by reduction in energy expenditure, including reduced physical activity, as well as by mobilization of bodily soft tissue. However, daily energy expenditure of lactating women has been shown to increase across the course of lactation among women in a rural population in the Philippines and an urban population in India, with a decline in body weight across the course of lactation in both studies. In the present study, total daily energy expenditure and anthropometric body composition were measured longitudinally in 68 mothers from a poor urban area of Dhaka, Bangladesh, at 0, 1, 2, 4, and 8 months of lactation, to determine whether the increasing energy expenditure across lactation observed elsewhere also occurs in Bangladeshi women. In addition, the extent to which an extended period of lactation was accompanied by weight and body fat change in these women was determined. Energy expenditure by heart-rate monitoring and activity report, and body composition from anthropometry was carried out four times across the 8-month period of lactation. A small decline in body fat mass and a significant increase in total energy expenditure across this period were observed, confirming similar observations elsewhere in the developing world.     

Regional body composition changes in women after 6 months of periodized physical training.

Data are lacking regarding regional morphological changes among women after prolonged physical training. This study employed dual-energy X-ray absorptiometry to assess changes in whole body and regional (i.e., trunk, legs, arms) fat mass, lean mass, and bone mineral content body composition adaptations in 31 healthy women pre-, mid-, and post-6 mo of periodized physical training. These results were compared with those of 1) a control group of women who had not undergone the training program and were assessed pre- and post-6 mo and 2) a group of 18 men that was tested only once. Additionally, magnetic resonance imaging was used to assess changes in muscle morphology of the thigh in a subset of 11 members of the training group. Physical training consisted of a combination of aerobic and resistance exercise in which the subjects engaged for 5 days/wk for 24 wk. Overall, the training group experienced a 2.2% decrease, a 10% decrease, and a 2.2% increase for body mass, fat mass, and soft tissue lean mass, respectively. No changes in bone mineral content were detected. The women had less of their soft tissue lean mass distributed in their arms than did the men, both before and after the women were trained. Novel to this study were the striking differences in the responses in the tissue composition of the arms (31% loss in fat mass but no change in lean mass) compared with the legs (5.5% gain in lean mass but no change in fat mass). There was a 12% fat loss in the trunk with no change in soft tissue lean mass. Dual-energy X-ray absorptiometry and magnetic resonance imaging fat mass measurements showed good agreement (r = 0. 72-0.92); their lean mass measurements were similar as well, showing approximately 5.5% increases in leg lean tissue. These findings show the importance of considering regional body composition changes, rather than whole body changes alone when assessing the effects of a periodized physical training program.     

Drinking water is associated with weight loss in overweight dieting women independent of diet and activity

Background: Data from short‐term experiments suggest that drinking water may promote weight loss by lowering total energy intake and/or altering metabolism. The long‐term effects of drinking water on change in body weight and composition are unknown, however. Objective: This study tested for associations between absolute and relative increases in drinking water and weight loss over 12 months. Methods and Procedures: Secondary analyses were conducted on data from the Stanford A TO Z weight loss intervention on 173 premenopausal overweight women (aged 25–50 years) who reported <1 l/day drinking water at baseline. Diet, physical activity, body weight, percent body fat (dual‐energy X‐ray absorptiometry), and waist circumference were assessed at baseline, 2, 6, and 12 months. At each time point, mean daily intakes of drinking water, noncaloric, unsweetened caloric (e.g., 100% fruit juice, milk) and sweetened caloric beverages, and food energy and nutrients were estimated using three unannounced 24‐h diet recalls. Beverage intake was expressed in absolute (g) and relative terms (% of beverages). Mixed models were used to test for effects of absolute and relative increases in drinking water on changes in weight and body composition, controlling for baseline status, diet group, and changes in other beverage intake, the amount and composition of foods consumed and physical activity. Results: Absolute and relative increases in drinking water were associated with significant loss of body weight and fat over time, independent of covariates. Discussion: The results suggest that drinking water may promote weight loss in overweight dieting women.     

Impact of the age at menarche on adult body composition in healthy pre- and postmenopausal women

The present study focuses on the impact of age at menarche on body composition development during adulthood. With 459 healthy middle-class women between 18 and 67 years (x = 41.5) the association between age at menarche and body composition was tested. Body composition, described by absolute and relative amount of fat mass, lean body mass, and bone mass, was estimated by means of dual energy x-ray absorptiometry. In order to exclude the influence of the menopausal transition on body composition, pre- and postmenopausal females were examined separately. The absolute amount of body fat was significantly lower within the group of women whose menarche occurred later. However, postmenopausal females exhibit less significant relations between the two trait systems than premenopausal women. This may be due to the impact of menopausal transition which affected the hormone levels and body composition development independently from the adolescent hormonal transition. While in both proband groups the quantitative amount of body fat was significantly related to menarcheal age, a significant relation between menarcheal age and adult body fat distribution could not be verified. Am J Phys Anthropol 105:9–20, 1998. © 1998 Wiley-Liss, Inc.     

Determinants of insulin-resistant phenotypes in normal-weight and obese Black African women

Objective: Subsets of metabolically “healthy obese” and “at‐risk” normal‐weight individuals have been previously identified. The aim of this study was to explore the determinants of these phenotypes in black South African (SA) women. Methods and Procedures: From a total of 103 normal‐weight (BMI ≤ 25 kg/m²) and 122 obese (BMI ≥ 30 kg/m²) black SA women, body composition, fat distribution, blood pressure, fasting glucose levels, insulin resistance, and lipid profiles were measured. Questionnaires relating to family history, physical activity energy expenditure (PAEE), and socio‐demographic variables were administered. The subjects were classified as insulin sensitive or insulin resistant according to the homeostasis model assessment of insulin resistance (HOMA‐IR) (≥1.95 insulin resistant). Results: Our study showed that 22% of the normal‐weight women were insulin resistant and 38% of the obese women were insulin sensitive. Increased visceral adipose tissue (VAT) (P = 0.001) and decreased VAT/leg fat mass (P ≤ 0.001), independent of total body fatness, distinguished between the phenotypes. Moreover, the insulin‐sensitive women were of higher socioeconomic status, did more leisure and vigorous PAEE and were less likely to use injectable contraceptives. Using a regression model, body fat distribution, percent body fat, age, log leisure PAEE, and use of injected contraception accounted for 35% of the variance in HOMA‐IR in the normal‐weight women. In the obese women, 34% of the variance in HOMA‐IR was explained by the same variables, excluding PAEE. No differences in smoking status or family history of metabolic disease were found between the phenotypes. Discussion: Central fat distribution, total adiposity, socioeconomic status, leisure PAEE, and use of injectable contraceptives distinguished between insulin‐sensitive and insulin‐resistant black SA women.     

Body composition determinants of metabolic phenotypes of obesity in nonobese and obese postmenopausal women

Objective : Although obesity is typically associated with increased cardiovascular risk, a subset of obese individuals display a normal metabolic profile (“metabolically healthy obese,” MHO) and conversely, a subset of nonobese subjects present with obesity‐associated cardiometabolic abnormalities (“metabolically obese nonobese,” MONO). The aim of this cross‐sectional study was to identify the most important body composition determinants of metabolic phenotypes of obesity in nonobese and obese healthy postmenopausal women. Design and Methods : We studied a total of 150 postmenopausal women (age 54 ± 7 years, mean ± 1 SD). Based on a cardiometabolic risk score, nonobese (body mass index [BMI] ≤ 27) and obese women (BMI > 27) were classified into “metabolically healthy” and “unhealthy” phenotypes. Total and regional body composition was assessed with dual‐energy X‐ray absorptiometry (DXA). Results : In both obese and nonobese groups, the “unhealthy” phenotypes were characterized by frequent bodyweight fluctuations, higher biochemical markers of insulin resistance, hepatic steatosis and inflammation, and higher anthropometric and DXA‐derived indices of central adiposity, compared with “healthy” phenotypes. Indices of total adiposity, peripheral fat distribution and lean body mass were not significantly different between “healthy” and “unhealthy” phenotypes. Despite having increased fat mass, MHO women exhibited comparable cardiometabolic parameters with healthy nonobese, and better glucose and lipid levels than MONO. Two DXA‐derived indices, trunk‐to‐legs and abdominal‐to‐gluteofemoral fat ratio were the major independent determinants of the “unhealthy” phenotypes in our cohort. Conclusions : The “metabolically obese phenotype” is associated with bodyweight variability, multiple cardiometabolic abnormalities and an excess of central relative to peripheral fat in postmenopausal women. DXA‐derived centrality ratios can discriminate effectively between metabolic subtypes of obesity in menopause.     

Physiological predictors of leptin vary during menses and ovulation in healthy women

Although research has shown interactions between the reproductive system and energy homeostasis, it is not clear how environmental or behavioral factors may factor into these associations. Here we aimed to determine how changes in reproductive state (i.e., phase of the menstrual cycle) and other behavioral and physiological factors may influence leptin levels in healthy women, as well as how sexual activity may play a role in leptin modulation. We collected serum and saliva from 32 healthy women and measured leptin, estradiol, and progesterone. Participants also completed surveys of demographics, health and sexual behaviors, and physical activity. Leptin was predicted by meals per day and missed meals at both menses and ovulation. However, estradiol and physical activity were stronger predictors of leptin at menses, while sexual activity was a stronger predictor of leptin at ovulation. These findings suggest that predictors of serum leptin, and possibly energy storage and expenditure, vary across the menstrual cycle.     

Body size satisfaction and physical activity levels among men and women

Body size satisfaction may be an important factor associated with physical activity. We analyzed data from the 2002 National Physical Activity and Weight Loss Survey (NPAWLS), a population-based cross-sectional telephone survey of US adults. Multiple logistic regression models were used to examine the association of body size satisfaction on being regularly active. Participants were aged > or =18 years with complete data on weight, race/ethnicity, physical activity level, and body size satisfaction (n = 10,021). More than half of men (55.8%) and women (53.3%) who reported being very satisfied with the body size were regularly active. After adjustment for covariates, participants who reported being somewhat or not satisfied with their body size had a 13 and 44% lower odds of being regularly active, respectively, compared with those very satisfied with their body size. When stratified by race/ethnicity, this association remained in whites (P for trend <0.001), but became weaker and nonsignificant in blacks, Hispanics, or other racial/ethnic groups. Irrespective of actual weight, those who were satisfied with their body size were more likely to engage in regular physical activity than those less satisfied. Further research is needed to explore predictors of physical activity to reduce health disparities.     

Adiponectin is associated with bone mineral density in perimenopausal women.

The aim of the current investigation was to investigate any potential effect of fasting plasma adiponectin concentration on bone tissue, and to find possible relationships of fasting plasma adiponectin level with different body composition, insulin sensitivity and physical performance parameters in a group of healthy perimenopausal women. Twenty-one premenopausal and 17 early postmenopausal women participated in this study. The women were matched for body mass index (BMI) and level of mean daily energy expenditure. Women had similar adiponectin (8.4 +/- 3.9 vs. 9.9 +/- 5.4 microg/ml) and leptin values (12.0 +/- 7.7 vs. 14.0 +/- 8.2 ng/ml) before and after menopause. Significant relationships were observed between plasma adiponectin and bone mineral content, total bone mineral density (BMD) and lumbar spine BMD values (r > - 0.36; p < 0.05). Furthermore, adiponectin had a significant negative association with total BMD (beta = - 1.228; p = 0.004) and lumbar spine BMD (beta = - 0.312; p = 0.005) independent of the influence that other measured body compositional, hormonal or physical performance factors may exert on BMD. Adiponectin was also significantly related to waist-to-hip ratio (WHR) (beta = - 2.300; p = 0.002) and fasting insulin resistance index (FIRI) (beta = - 0.006; p = 0.007) in separate regression models. No relationship was observed between leptin and measured bone, physical performance and insulin resistance values. Leptin significantly correlated to BMI (beta = 0.018; p = 0.034), lean body mass (beta = 0.025; p = 0.024) and fat mass (beta = 0.019; p = 0.001) in separate regression models. In conclusion, the results of present study show that circulating adiponectin appears to exert an independent effect on BMD in perimenopausal women and may represent a link between adipose tissue and bone mineral density.     

Diet composition and activity level of at risk and metabolically healthy obese american adults

Objective:

Obesity often clusters with other major cardiovascular disease risk factors, yet a subset of the obese appears to be protected from these risks. Two obesity phenotypes are described, (i) “metabolically healthy” obese, broadly defined as body mass index (BMI) ≥ 30 kg/m² and favorable levels of blood pressure, lipids, and glucose; and (ii) “at risk” obese, BMI ≥ 30 with unfavorable levels of these risk factors. More than 30% of obese American adults are metabolically healthy. Diet and activity determinants of obesity phenotypes are unclear. We hypothesized that metabolically healthy obese have more favorable behavioral factors, including less adverse diet composition and higher activity levels than at risk obese in the multi‐ethnic group of 775 obese American adults ages 40‐59 years from the International Population Study on Macro/Micronutrients and Blood Pressure (INTERMAP) cohort.

Design and Methods:

In gender‐stratified analyses, mean values for diet composition and activity behavior variables, adjusted for age, race, and education, were compared between metabolically healthy and at risk obese.

Results:

Nearly one in five (149/775 or 19%) of obese American INTERMAP participants were classified as metabolically healthy obese. Diet composition and most activity behaviors were similar between obesity phenotypes, although metabolically healthy obese women reported higher sleep duration than at risk obese women.

Conclusions:

These results do not support hypotheses that diet composition and/or physical activity account for the absence of cardiometabolic abnormalities in metabolically healthy obese.     

IAAT, catecholamines, and parity in African-American and European-American women

Objective: We have recently reported that parous European‐American (EA) women have disproportionately more intra‐abdominal adipose tissue (IAAT) than their nulliparous counterparts. Mediating mechanisms for IAAT accumulation remain unknown; however, some evidence suggests a possible catecholamine link. The objective of this study was to determine whether the IAAT‐parity relationship found in EA women exists in African‐American (AA) women and to determine whether catecholamines play a mediating role. Methods and Procedures: Subjects included 44 EA and 47 AA premenopausal women. Free‐living physical activity by doubly labeled water (activity‐related time equivalent (ARTE)), body composition (air plethysmography, computed tomography), and 24‐h fractionated urinary catecholamines were measured. Results: Repeated measures ANOVA revealed parous EA and AA women had significantly higher IAAT than their nulliparous counterparts (100.1 ± 28.5 and 76.2 ± 34.8 cm² vs. 75.9 ± 29.1 and 59.6 ± 15.0 cm²). In AA women and nulliparous women, 24‐h urinary dopamine was significantly higher (AA parous 260.8 ± 88; EA parous 197.2 ± 78.8; AA nulliparous 376.5 ± 81; EA nulliparous 289.6 ± 62). Multiple regression analysis for modeling IAAT indicated that race, parity, dopamine, ARTE, and VO_2max were all significant and independent contributors to the model (Unstandardized βs: race ?32.6 ± 7.4; parity (number of births) 10.0 ± 3.4; 24‐h urinary dopamine 0.08 ± 0.04; ARTE (min/day) ?0.09 ± 0.04; VO_2max (ml/kg/min) ?2.8 ± 1.0). Discussion: Independent of the potential confounders: age, race, percent body fat, IAAT, 24‐h fractionated urinary catecholamines, physical activity, and VO_2max, parous EA and AA women had more IAAT than their nulliparous counterparts. Of the catecholamines, dopamine was found to be significantly lower in parous women and higher in AA's. Dopamine, however, did not explain racial or parity differences in IAAT.     

Cardiovascular, anthropometric and neurocognitive features of healthy postmenopausal women: effects of hormone replacement therapy

Randomized clinical trials have not shown long-term benefit of postmenopausal hormone replacement therapy (PHT) nor have they shown conclusively that the harmful consequences outweighs the benefits of the treatment. Rather, it is possible that an individualized hormone replacement therapy in questionably clinically healthy postmenopausal women may lead to different results than randomized trials. DESIGN: In this cross-sectional study we evaluated anthropometric parameters, body composition, serum lipids, blood pressure, heart rate variability (HRV) and neurocognitive functions in 39 healthy postmenopausal women PHT users or not users (n=13, age 53.0+/-3.3 and n=26, age=53.3+/-5.0 SD, respectively) as well as in 27 younger controls (ages=33.3+/-7.1). RESULTS: Demographic parameters were similar in women PHT users and not users. Postmenopausal women showed a significantly increase of body mass index (BMI) as well as of waist circumference, compared to younger controls, but in PHT users the values of fat free mass were intermediate between the ones of not treated and younger women. The study of HRV showed a reduction in low frequency (LF) component (sympathetic modulation) during the day, and a reduction in high frequency (HF) component (parasympathetic modulation), particularly in postmenopausal women without PHT. PHT users were characterized by autonomic parameters intermediate between younger controls and age-matched women without PHT. CONCLUSIONS: The impact of PHT on the age-dependent changes of anthropometric features and body composition seems to be modest but positive. Furthermore, PHT seems to play a positive role on the autonomic modulation of cardiac function, through a shift of LF/HF ratio values towards those of young controls.     

Turnover of plasma free arachidonic and oleic acids in men and women.

The turnover of plasma free arachidonic and oleic acids was determined in healthy men and women. The plasma pool of arachidonic acid in the men was 75 per cent higher than in the women. The fractional turnover of arachidonate was 0.80 +/- 0.04 min(-1) in the women and 0.47 +/- 0.04 min(-1) in the men. The turnover rate of arachidonic acid was similar in both sexes; calculated per kg body weight it was significantly higher in the women. No sex differences were observed in the concentration or turnover of plasma free oleic acid when corrected for differences in body size. The composition of the free fatty acid fraction differed between the sexes, the female subjects having a lower proportion of saturated fatty acids and higher proportions of oleic and eicosenoic acids. The results indicate that the metabolism of polyunsaturated fatty acids in man is influenced by gonadal steroid hormones.     

Growth hormone enhances effects of endurance training on oxidative muscle metabolism in elderly women

The present study investigated whether recombinant human (rh) growth hormone (GH) combined with endurance training would have a larger effect on oxidative capacity, metabolism, and body fat than endurance training alone. Sixteen healthy, elderly women, aged 75 yr, performed closely monitored endurance training on a cycle ergometer over 12 wk. rhGH was given in a randomized, double-blinded, placebo-controlled design in addition to the training program. GH administration resulted in a doubling of serum insulin-like growth factor I levels. With endurance training, peak oxygen uptake increased by approximately 18% in both groups, whereas the marked increase in muscle citrate synthase activity was 50% larger in the GH group compared with the placebo group. In addition, only the GH group revealed an increase in muscle L-3-hydroxyacyl-CoA dehydrogenase activity. Body weight remained unchanged in both groups, but the GH group showed significant changes in body composition with a decrease in fat mass and an increase in lean body mass. Twenty-four-hour indirect calorimetry performed in four subjects showed a marked increase in energy expenditure with increased relative and absolute fat combustion in the two subjects receiving rhGH. In conclusion, rhGH adds to the effects of endurance training on muscle oxidative enzymes and causes a reduction in body fat in elderly women.     

Subcutaneous adipose tissue pattern in lean and obese women with polycystic ovary syndrome

The new optical device, Lipometer, permits the noninvasive, quick, safe, and precise measurement of the thickness of subcutaneous adipose tissue (SAT) layers at any given site of the human body. Fifteen anatomically well-defined body sites from neck to calf describe the SAT topography (SAT-Top) like an individual "fingerprint." SAT-Top was examined in 33 women with polycystic ovary syndrome (PCOS), in 87 age-matched healthy controls and in 20 Type-II diabetic women. SAT-Top differences of these three groups were described, and, based on a hierarchical cluster analysis, two distinctly different groups of PCOS women, a lean (PCOS(L)) and an obese (PCOS(O)) cluster, were found. For visual comparison of the different types of body fat distribution, the 15-dimensional body fat information was condensed to a two-dimensional factor plot by factor analysis. For comparison of the PCOS like body fat distribution with the "healthy" fat pattern, the (previously published) SAT-Top results of 590 healthy women and men (20-70 years old) and 162 healthy girls and boys (7-11 years old) were added to the factor plot. PCOS(O) women showed a SAT-Top pattern very similar to that of women with Type-II diabetes, even though the diabetic women were on average 30 years older. Compared with their healthy controls, SAT-Top of these PCOS(O) patients was strongly skewed into the android direction, providing significantly decreased leg SAT development and significantly higher upper body obesity. Compared with healthy women, PCOS(L) patients had significantly lower total SAT development (even though height, weight, and body mass index did not deviate significantly), showing a slightly lowered amount of body fat in the upper region and a highly significant leg SAT reduction. This type of fat pattern is the same as found in girls and boys before developing their sex specific body fat distribution. We conclude that women with PCOS develop an android SAT-Top, but compared in more detail, we found two typical types of body fat distribution: the "childlike" SAT pattern in lean PCOS patients, and the "diabetic" body fat distribution in obese PCOS women.     

Blood flow response to a postural challenge in older men and women

BACKGROUND: The purpose of this study was to measure blood flow in the carotid and femoral arteries, heart rate and blood pressure in response to postural challenge in older adults. A second purpose was to determine if older men and women have different cardiovascular responses to a postural challenge such as tilt. METHODS: Thirty-seven healthy elderly men and women participated in this study (69-82 years old). All subjects had similar physical activity levels. Postural challenge was induced by a 60 degrees tilt at the level of the waist. Continuous carotid blood flow and femoral blood flow was measured with Doppler ultrasound. RESULTS: Carotid blood flow was significantly reduced 17% in both men and women immediately after tilt (p < 0.001), and by 3.2% two minutes after tilt (p < 0.001). Femoral blood flow decreased 59.4% in men and 61% in women immediately after tilt (p < 0.001), and remained significantly decreased two minutes after tilt by 21% (p <0.001). Heart rate increased by 15% in men (p < 0.001), and 26% in women immediately after the tilt (p < 0.001). Heart rate returned to resting values within two minutes in both men and women. Response to tilt was not significantly related to self-report physical activity levels or to six-minute walk time. CONCLUSION: A postural challenge induced larger changes in the femoral artery compared to the carotid artery. There were no differences between men and women to a tilt table test except for differences in heart rate response. There was no difference in the blood flow responses to postural challenge with physical activity level or between healthy older men and women.     

Determinants of insulin-stimulated glucose disposal in middle-aged, premenopausal women

Controversy exists regarding the relative importance of adiposity, physical fitness, and physical activity in the regulation of insulin-stimulated glucose disposal. To address this issue, we measured insulin-stimulated glucose disposal [mg. kg fat-free mass (FFM)(-1). min(-1); oxidative and nonoxidative components] in 45 nondiabetic, nonobese, premenopausal women (mean +/- SD; 47 +/- 3 yr) by use of hyperinsulinemic euglycemic clamp (40 mU. m(-2). min(-1)) and [6,6-2H2]glucose dilution techniques. We also measured body composition, abdominal fat distribution, thigh muscle fat content, maximal oxygen consumption (VO2 max), and physical activity energy expenditure ((2)H(2)(18)O kinetics) as possible correlates of glucose disposal. VO2 max was the strongest correlate of glucose disposal (r = 0.63, P < 0.01), whereas whole body and abdominal adiposity showed modest associations (range of r values from -0.32 to -0.46, P < 0.05 to P < 0.01). A similar pattern of correlations was observed for nonoxidative glucose disposal. None of the variables measured correlated with oxidative glucose disposal. The relationship of VO2 max to glucose disposal persisted after statistical control for FFM, percent body fat, and intra-abdominal fat (r = 0.40, P < 0.01). In contrast, correlations of total and regional adiposity measures to insulin sensitivity were no longer significant after statistical adjustment for VO2 max. VO2 max was the only variable to enter stepwise regression models as a significant predictor of total and nonoxidative glucose disposal. Our results highlight the importance of VO2 max as a determinant of glucose disposal and suggest that it may be a stronger determinant of variation in glucose disposal than total and regional adiposity in nonobese, nondiabetic, premenopausal women.